Sewing machine



June 26, 1956 M, sc w 2,751,868

SEWING MACHINE Filed June 19. 1953 4 Sheets-Sheet 1 I I I *l V 9 "1 i l L. E 32 I 1 z J #792 I 15 76' 20 e 78 k 7 as 'm enar': MAX 5(flWA6 a fl y fi.

M. SCHWAB SEWING MACHINE June 26, 1956 4 Sheets-Sheet 2 Filed June 19, 1953 Inventor MAX 5(//WA6 M. SCHWAB SEWING MACHINE June 26, 1956 4 Sheets-Sheet 3 Filed June 19. 1953 Inventor: MA X .Scl/WAAB June 26, 1956 M. SCHWAB 2,751,858

SEWING MACHINE Filed June 19, 1953 4 Sheets-Sheet 4 1N VEN TOR.

GENT

United States Patent 6 SEWING MACHINE Max Schwab, Schwetzingen, Germany Application June 19, 1953, Serial No. 362,868

Claims priority, application Germany June 20, 1952 8 Claims. (Cl. 112210) This invention relates to certain improvements in sewing machines and has special reference to a device for chwging over from forward sewing to reverse sewing and for semi-automatic locking of a seam sewn by the machine.

It is an object of the present invention to provide means for facilitating the operation of such a device and for ensuring a reliable operation thereof.

In a sewing machine according to the present invention the change-over between forward sewing and reverse sewing is effected by means of an electromagnet acting upon the stitch-setting means. This electromagnet may be energized under the control of a member which can be operated at will, for example a lever to be operated by the seamstress with her knee. Changes between forward and reverse sewing can then be effected quickly, conveniently and in operationally reliable manner by contact closure without the seamstress having, as hitherto, to operate by hand the stitch-setting means usually provided on the superstructure of the machine. Consequently, even for these changes, she can leave her hands on the material being sewn by the machine and can thus ensure accurate guidance of the said material.

This device proves particularly advantageous in the locking of a seam sewn by the machine. This operation is performed by sewing a certain number of stitches, for example four stitches, in a forward direction and then the same number of stitches in a reverse direction.

For the purpose of semi-automatic locking of the seam a control device which acts upon an auxiliary drive, im parting to the sewing machine a speed lower than that derived from the normal main drive means is controlled by a switch device by which the circuit of the control device can be closed or opened at will for the duration of more than one revolution of the machine shaft. The means for elfecting the reverse sewing is also rendered operative by an electromagnet included in the circuit of the control device. Thus, the circuit of'a control device is controlled by a contact device in such a way, after the main drive has been disconnected, that this control device continues to impart rotary motion to the machine shaft, at a substantially reduced speed, as far as a desired dead-centre position of the needle of the sewing machine. This contact device also causes the reverse sewing of the sewing machine.

In accordance with the operation of this invention the knee lever of the contact device is actuated a distance of one notch of a ratchet wheel during operation of the sewing machine. The sewing machine continues to stitch with suitably reduced, but constant, speed as long as a predetermined pressure is exerted upon the knee lever of the contact device. When the desired number of stitches have been sewn, the contact device is actuated to a further notch of the ratchet wheel by means of the knee lever. In this latter position the control device is inactive for a short time while the contact device changes over the sewing machine to reverse sewing. If the contact device is again advanced through one step, i. e., to

the next detent of the ratchet wheel, the sewing machine will sew in a reverse direction at a suitably reduced but constant speed. This type of actuation of the contact device can be repeated as often as desired. It the material being sewn is in a position requiring reverse sewing for locking the seam, the main drive is disengaged in such a way that a few stitches can still be sewn with the control device. To accomplish this reverse sewing, the contact device has to be moved to the first detent of the ratchet wheel. If now the knee lever is set to the second detent of the ratchet wheel, it is possible to lock the seam in the manner described above.

In the above described device it is necessary to exert permanent control pressure upon the lever engaged in the respective notch. In case of a reduction of the control pressure exerted on the contact device the controller cylinder would return to its initial position, whereby the cycle of operations would be interrupted.

It is an important object of the present invention to provide additional means rendering it unnecessary to exert such permanent control pressure.

With this special object in mind, the contact device according to the present invention is constructed in such a Way that the control pressure is exerted upon a ratchet wheel, through a pawl which is connected with the knee lever of the contact device. The ratchet wheel is directly connected with a toothed wheel which drives a controller cylinder at a suitable predetermined reduced speed. The controller cylinder is constructed in such a way that it is automatically stopped by the pressure of the contact springs in each of the contact and zero positions of the controller cylinder. On the other hand the pitch of the ratchet wheel according to the invention is adapted in such a way that the pawl is able to engage the succeeding tooth of the ratchet wheel only when the required number of contact positions of the controller cylinder has been passed and the controller cylinder is again in its zero position. A return spring on the pawl moves the control lever into an end position if no control pressure is exerted. However, a new cycle of switching operations can be initiated only when, as described above, all switch positions of the first cycle of contacts have been passed.

According to a further feature of the present invention the contact shaft is operating on the free wheel principle. If no control pressure is exerted, the contact shaft need not return to its initial position, but it can remain in its position until a new control pressure is exerted.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and appear in the appended claims forming part of the application.

In the accompanying drawings a now preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

Fig. 1 is a longitudinal section on line II of Fig. 3,

Fig. 2 is a section on line II--II of Fig. 1,

Fig. 3 is a section on line lIIIII of Fig. 1,

Fig. 4 is a section on line IV-IV of Fig. 1,

Fig. 5 is a side view of the controller cylinder with the current carrying contacts,

Fig. 6 is a development of the controller cylinder, the position of the current carrying contacts corresponding to the position A of the control lever,

Fig. 7 is a diagrammatic view of the contact device with its control lever and the circuit diagram, including the circuit for an electromagnet and the circuit for the control device, the controller cylinder in this case being in.

the position A, Fig. 8 is a diagrammatic view similar to Fig. 7, showing the controller cylinder only, in the position B,

Fig; 9 is a diagrammatic View of the controller cylinder in the position C, p I

Fig. is a diagrammatic view of the controller cylinchar in the position D', and' Fig. 11 is a diagrammatic view of the controller cylinder' in. theposition; E which. corresponds. to. position. A Fi'g l2..illustrates one embodiment of thepresent inven: tionas appliedltoa sewing machine,.

Eig 13'is a left end view of. thestructure; illustrated.' in Fig. 12, and.

Fig. 14 isan enlarged sectional. view of .the stitch set-.-

tihg screw shown iniFi gs. l2 and-I13v taken. along the line. 141'iiin.Fig. 12L Similar reference numerals denote similar. parts in. the diflErent views.

Referringnowto the. drawings: in greater detail, it. willbe seen that the contactdevicetor semiautomatic. loc"-. ing. of the. seam comprises a shaft. 2" which is filredi'y arranged. in. a casing ori frame 11 Shaft 2 may be threaded at one endthereoftoreceive a boit 3. for clamp ing .shaft2 to. frame. 1.. Rotatably mounted on the shaft 2.is abodyof insulating. material preferably consisting of two parts 4, 5' and'beingarrested. in an axial direction by means ofa setting ring.6= and a Worm screw 7 The insulating body is formed with flanges 8 and 9 in whose circular recesses are inserted contact pins 10, 11, 12, 13, 1.4 and 15. Provided" on the. circumference of theinsulatingbody 4 are cams 1'6, 17, 18; 1?, 29, and

21: which are shaped in such a way as to engageinto a depressionof a correspondingly shaped contact springs 22 ,23, Fig. 2. In an analogous. Way the insulating body 5 is formed with circularly shaped earns 24, 25'; 26, adapted; to engage in a depression of a correspondingly shaped contact spring 27. The body 5' is provided with apinion ZS-meshing with a toothed wheel 29., which is rotatably mounted on a pin. 3% and formed integral with aratchet-wheel 31. The control lever 32'is also mounted on; the pin 30. and formedwith an extension 33 on which a pawl. 34. is. mounted which falls into the ratchet wheel 31 by it's own weight. against. the control pressure. exerted by the knee of the seamstress,.by a spring 35 which is suspended from a lug 36 0f the. extended control lever 32 and secured on a projection 37 in. the part 38 of the casing-by means. of a screw 39; The part 1 of the casing is secured to the part 38. thereof by screws 40,41, 42.

The operation is as-follows:

In Figs. 1 to 7 the control lever 32 is shown in thepositionA whichcorresponds to the zeroposition of the controller cylinder. The cycle of switching operations comprises four. positions. hereinafter referred to. as position.

A, B', C, D. The endiposition-E ensures the correct posi- 3 tion o'f the ratchet wheel 31 for the beginning of a new cycle. Intheposition shown in Figs. 1v to 7 the current carrying springs122, 23; 27 engage over the cam 18 corresponding tov the zero position. is connected if the. current carrying springs 22, 23' are shortscircuited. The. electro magnet 45' is connected when the current carrying springs 23; 21 are short-circuited and effects changing over. of the feed? of' the sewing machine from forward. to reverse.

If the control-lever 32 is moved into the positionB by the knee, the controller'cylinder' is rotated through the ratchet: wheel. 31 and the pinions'29, 28, until the springs 22', 2'3 engage over the contact bar 12, Fig. 81 The current carrying spring 27 slides on the slideway 43 of the insulating body 5. The springs 22, .23 forming contacts are short-circuited by the contact pin 12', so. that the controldevice is started andthe sewing machine is. driven at a predetermined. low number of stitches, so that it is possible to sew forward, as long, as the contact. device remains. in the position B? (see Fig; 8) troller cylinder is turned into the position C, the current carrying springs 22, 23 engage over the'insulating cam 19 (see Fig. 9)., so that the; supply of current to the con.- trol device is interrupted and: the: needle: or the: needle bar is automatically moved into a desired dead-centre:

The control lever 32 is acted upon,

The control device. 44'

Now, if. the; con.-

' lever is moved into the position E.

position, e. g. the upper dead-centre position. During these operations the current carrying contact ZTremains on the slideway 43.

If the controller cylinder is rotated into the position D, the current carrying springs 22, 23, 27 will engage over the contact pin 13, Fig. 10. circuit for the control device and the circuit for the electromagnet 45 is closed, with the result that the sewing machine will continue to run at a speed corresponding to a predeterminednumber of stitches; is changed over to reverse. under action of the electromagnet 45; so that in this position any number of stitches can be; sewn inthe reverse direction until the; control In position E all of the three contacts engagecverthe insulating cam 2t) and all of the circuits are interrupted,.Fig. 11. Here again the needle bar will take up a desired dead-centre position, for example, the. upper one... In. the. position E the ratchet wheelSl reaches a position. which renders. it. possible that the pawl 34 can engage the. next tooth, since the. positions AD are within one. pitch unit'offthe ratchet Wheell The controller cylinder accordingly is practically again in its zero position. and the said cycle of operations can be repeated any number ofv times.

through the contact pin 14, the insulati'ngcarn 21, con tactpin 15, insulating cam 16. etc;

In order to have the possibility, independently of. the. said contact device, of'changing the feed.- to reverse. by a corresponding adjustment of'the electromagnet 45,. according to the invention a switch 46 is provided. If. said switch 46, Figs. 7; lZZand 13 is operated, for in: stance, by manual or by pedal pressure or by Bowden. control; the circuit for the electromaguet is closed, independently of the actual position of the controller cylinder. However, it is also possible to. change the direction of speed mechanically, e. g. by a knee lever, by Bowden control or by similar means.

Fig, 12 illustrates. asewing. machine embodying they present invention, and. comprisinga superstructure 5% having a flywheel 5i and a. groovedpulley- 52 mounted on a drive shaft53. Driveshaft 53 is rotatably attached to superstructure 59 and; is actuated by an electric motor 54 through. a. grooved. pulley 55 and a pulley belt 56. Motor 54 is controlled. by asclutci 57 which is actuated by a lever 53 pivotally connected by. a pull rod 59 to. a foot pedal 66'. Pedal 6t v ismounted so, that it can be tilted sideways as well as. turned about trunnions. 6.1

and 62 in.th'e. known manner: to bring to rest the needle in the upper or lower. dead-center position.

The controL device 44 is, connected to shaft. 53 by, a suitable. grooved pulley 63' and imparts by an auxiliary drive mechanism therein when motor. 54. is disconnected] from shaft 55 a. speed lower than that. derived from the normal main. drive motor 54%.. Device. 4.4. is. controlled. byythe. contact device disclosed and housed incasing. or frame 1. Device 44further. controls and effects the reverse sewing by controlling the circuits which energized. the electromagnetAS: a

The electromagnet. 45;- is mounted on the; superstruc.- ture50. (-asshown in Fig. 12.) and acts vertically on the stitch setting screw- 65. Asshown in: Figs. 13 and 14 the neck of screw 65 is' embraced by a collet 6'6 held together by a pin- 67. The; pin is secured in an elongated slot- 6'8 in an actuating fork 69* of the electromagnet 4501* of a: pull rod.70. The actual reversing movement of the stitch setting screw is. wellknown. in the art and will not' be needed herein to fully understand the invention claimed.

7 While. the. inventionhas. been descrihedin detail. with respect. to a-no.w preferred. example and ernhochrnentot the; invention. it. willbe. understood by those skilled. in. the art? after. understanding the invention that various. changes-- and modifications may. be made without departing from the'spirit and scope of. the invention and; it is in this case both the The feed intended, therefore, to cover all such changes and modifications in the appended claims.

I claim:

1. In an electrically operated and electromagnetically controlled sewing machine employing a main drive member operable at a predetermined speed the combination comprising an auxiliary drive member for actuating said machine at a reduced speed, a stitch setting means for changing said machine over between forward and reverse sewing of said machine, an electromagnet for actuating said stitch setting means when energized to eifect changes in sewing direction of said machine, a control device adapted to actuate said auxiliary drive member and switching means for correlating the action of said control device and said electromagnet comprising a lever operable by an operator, means connected to said lever to actuate said switching means in only one direction to selectively energize and deenergize said control device and said electromagnet in a given cycle of operation.

2. In an electrically operated and electromagnetically controlled sewing machine employing a main drive member operable at a predetermined speed the combination comprising an auxiliary drive member for actuating said machine at a reduced speed, a stitch setting means for changing said machine over between forward and reverse sewing of said machine, an electromagnet for actuating said stitch setting means when energized to efiect changes in sewing direction of said machine, an electric control device adapted to actuate said auxiliary drive member, switching means for correlating the action of said control device and said electromagnet comprising an insulating contact drum, a plurality of spaced contacts arranged on the circumference of said drum, electric circuits connecting said contacts to a source of electrical energy, spring contacts cooperating with said contacts arranged on the circumference of said drum and electrically connected to said control device and said electromagnet, and means actuable by an operator to actuate said drum to selectively energize and deenergize said control device and said electromagnet in a given cycle of operation.

3. In an electrically operated and electromagnetically controlled sewing machine employing a main drive member operable at a predetermined speed the combination comprising an auxiliary drive member for actuating said machine at a reduced speed, a stitch setting means for changing said machine over between forward and reverse sewing of said machine, an electromagnet for actuating said stitch setting means when energized to efiect changes in sewing direction of said machine, an electric control device adapted to actuate said auxiliary drive member, switching means for correlating the action of said control device and said electromagnet comprising an insulating contact drum, a plurality of spaced contacts arranged on the circumference of said drum, electric circuits connecting said contacts to a source of electrical energy, spring contacts cooperating with said contacts arranged on the circumference of said drum and electrically connected to said control device and said electromagnet, a lever operable by the knee of an operator, and a pawl mechanism connecting said lever with said drum to actuate said drum in only one direction to selectively energize and deenergize said control device and said electromagnet in a given cycle of operation.

4. An electrically operated and electromagnetically controlled sewing machine in accordance with claim 3 wherein the pawl mechanism is connected to said drum by means of a gear ratio transmission.

5. An electrically operated and electromagnetically controlled sewing machine in accordance with claim 3 wherein the operation of said lever is eifected against the action of a spring.

6. An electrically operated and electromagnetically controlled sewing machine in accordance with claim 3 wherein the pawl mechanism is connected to said drum by means of a gear ratio transmission the tooth distribution of the gears being arranged so that the pawl of the knee lever engages the next tooth of the gear transmission after a predetermined movement of said lever.

7. In an electrically operated and electromagnetically controlled sewing machine employing a main drive member operable at a predetermined speed the combination comprising an auxiliary drive member for actuating said machine at a reduced speed, a stitch setting means for changing said machine over between forward and reverse sewing of said machine, an electromagnet for actuating said stitch setting means when energized to effect changes in sewing direction of said machine, an electric control device adapted to actuate said auxiliary drive member, switching means for correlating the actions of said control device and said electromagnet comprising an insulating contact drum having indentations extending axial 1y thereof and rib-shaped projections arranged between said indentations and serving as rest cams, contact bars arranged within said indentations some of which are electrically connected to said control device and others of which are electrically connected to said electromagnet, spring contacts arranged to selectively engage said contact bars and said rest cams, electric circuits connecting said spring contacts to a source of electrical energy, said spring contacts upon actuation of said drum selectively energizing and deenergizing said control device and said electromagnet, and means operable by an operator to rotate said drum in only one direction a predetermined distance to selectively energize and deenergize said control device and said electromagnet in a given cycle of operation.

8. In an electrically operated and electromagnetically controlled sewing machine employing a main drive member operable at a predetermined speed the combination comprising an auxiliary drive member for actuating said machine at a reduced speed, a stitch setting means for changing said machine over between forward and reverse sewing of said machine, an electromagnet for actuating said stitch setting means when energized to efiect changes in sewing direction of said machine, a control device adapted to actuate said auxiliary drive member, switching means for correlating the action of said control device and said electromagnet comprising a lever operable by an operator, means connected to said lever to actuate said switching means in only one direction to selectively energize and deenergize said control device and said electromagnet in a given cycle of operation, and means comprising a switch connected to a source of electrical energy for energizing and deenergizing the electromagnet for the purpose of changing the direction of sewing of said machine independently of the particular position of said switching means.

References Cited in the file of this patent UNITED STATES PATENTS 2,005,656 Lasztoczy June 18, 1935 2,031,323 Lasztoczy Feb. 18, 1936 2,708,415 White May 17, 1955 FOREIGN PATENTS 1,059,104 France Mar. 23, 1954 1,074,064 France Oct. 1, 1954 

